I think my trucks an economy car!?!?

[5.3LSilverado01]

I was curious with all the air flow improvements I put on my truck, what kinda mpg's can I get driving 70mph, no flooring it, 4 gear passes only, accelerating as fast (I mean slow) as surronding traffic (truck drops into 4th around 40-45mph driving this way and don't rev over 1800rpm). I got around 25mpg in the day and 30mpg at night (4am coming home from work, 40-50 mile trip). 80-90mph I get anywhere from 18mpg(many passes) to 23mpg. 25-30mpg figures I did in my head while filling up at the gas station, so I'm going to try this again take down all #'s and use a calculator and post everything on here just to conferm my figures. As you might be able to tell, I can't spell worth SH!T, but i'm exelent at math, went straight into Trig. while freshman in college.

 

Either way, thats pretty dang incredible, espesially for a 4800lbs truck, almost full tank-o-gas, and me not in it. (I wieghed it at work with the semi-truck scale. It rounds to the nearest 10lbs).

 

On the other hand, when hauling butt, truck just drinks gas like crazy    

[HillHound]

Sounds high but given that your truck's a 2wd with 3.42s and all the mods it's maybe possible.   Dang-I'm lucky to see 15mpg with my 4.10s and all the hills.  If I keep it strictly interstate driving I can manage to break 17mpg :idontgetit: .

[ekonk]

That's just plain impressive. Keep us posted when you've repeated it, so we know it wasn't just a freak thing.

 

Just curious....do you have a toneau cover or anything that might improve aerodynamics?

[5.3LSilverado01]

No, I don't have a toneau cover. I do drive with the tail gate up. I remember in a Motor Trend mag they tested the mpg with gate up and the tail gate down, was a '99 2wd 5.3L ext cab, they found little to no difference.

 

I know that sounds crazy, but I'll drive 60miles (Brenham to Katy), and the gas needle won't even move. Floor the truck a few times and I'll loose a few gallons of fuel, haha. Well not really, i hope, but if every pass is a full throtle pass, then the needle will move about 1/8 or so.

 

No, I didn't get the 25-30mpg #'s from looking at the needle, got from gas pump and trip OD.

 

One of my favorite things to do while driving is coming up to someone doing about 60mph. I'll slow to 60 and wait till its clear, turn off the a/c, using my shifter, I'll put it down into 2nd gear (takes some practice to get that to be a smooth down shift), hit the blinker, and floor it. I'll take it up to 5,500rpm or 90mph then shift into 3rd, then 4th after all is said and done. I love to see the look on peoples faces when this ext cab truck, that sounds like a Vette on steroids, that was doing 60 only a few seconds ago, be doing 90 by the time my rear bumper passes there front bumper!!! Some people couldn't care less, some have this look on there face thats worth the 4 gallons of gas it took to do that!! The look that says "Gwwaaaaaaaaaa", the look of complete amazment! I love that. Espesially if its a ford or dodge truck HAHA!!

[carguru]

My '99 2wd ext cab, 5.3 bone stock with 3.73 locker would get 26-27 mpg highway cruising at 70 -75 mph.  I had a tonneu cover.  City driving would give me around 15-16 mpg. So it is possible to get better mileage with the mods you have since you've made the engine a more efficient air pump.

[Redapple]

Great milage numbers! I average about 15mpg in mixed and about 17-19 in pure hwy unloaded. I thought I was doing great. 4wd 5.3 w/3.73 diff.

 

Bill

[LarryE]

im always in the mid 20's   but with cold air, no maf screen, and bed cover I better be  lol

[Shaners]

With the mods you've done and the fact that your truck is 2wd and has 3.42 airplane gears it should deliver pretty good numbers.  If you live in a flat area of Texas and the fact that you are not driving any  short trips, this should help too...

[MarkD]

Awesome mileage numbers!  It is great to know what is possible.  I may have to try it to see how far I can stretch a tank.

[Stepside Z]

That is great milage. Strap a set of 285 BFGs on that thing and I'll bet money it goes down.  

[maestro1]

First of all, I want to thank you for posting your mileage numbers.  In another year, I plan on trading my 94 Nissan SE V-6 king cab for a Silverado or Sierra.  I do most highway driving with NO towing, so I am after something that will be comfortable, roomy, and also deliver good mpg's.  It sounds to me, that for my purposes, and 2wd extended cab would work out great with the 5.3 and 3.42 gears.  I do know  that our school district has one Suburban with the 3.42 gears and it will consistently deliver 18-21 mpg depending on who's driving it, LOL.    Thanks again for the info, I know now what my next truck will be.    Bob

[5.3LSilverado01]

I'm going to do this test again as soon as I need to fill up again. To keep results accurate-ish, I'm using the same gas station ("JUDS" Chevron on Hwy 36), and the same exact pump, not topping the tank off, and at the same time of day with, if possible, the same weather, mainly temp, conditions. Also this time, I'm going to keep all 4 tires at there max psi. If all 4 tires are 10 psi to low, you can loose up to 25% mpg's! There are going to be sometimes where I will have to get on it a bit (passing semi's or if I'm late to work or something), so the mpg #'s will be a little lower, but more accurate to daily driving conditions, rathers than all out mpg. For an all out mpg test, I'd have to do it closer to Houston where the max speed limit is 55mph, but how boring would that be.

 

Its fairly hilly on the way to work also...

 

My Truck seems to have a sweet spot it loves to cruise at. This speed varies from day to day, but is somewhere from 80-90mph. When at this speed, I'm barley touching the accelerator, barley hear any exhaust, and just feels completely smooth and friction-free, i guess. If I turn off the radio, I can literally hear my motor turning. This sound is also awsome! It sounds so perfectly refined and incredibly heathy.

 

Try this in a ford and one might (will) hear "jigga jigga jigga clunk jigga pop bang jigga jigga ................... Jigga ................... jigga jigga ................ Thank you for calling Ford road side assistance. Do to a rediculous amount of callers, an operator will be with you in aprox. 4 1/2 hours..."

 

   HAHAHA

[anealysr]

That is great gas mileage. I have a 98 GMC Z71 with a 5.7 or 350 for us old guys and I drive 89 miles one way to work everday. About 50/50 highway and city. I have gotten 20.2 taking it easy. I average about 19.6 without the a/c and 18.8 running the a/c. Please post the mods so I can get some ideas. Thanks